The present invention relates to a corrugating system for the manufacture of a corrugated paperboard web and, more particularly,, to a thread-up apparatus particularly useful in a corrugator double backer utilizing a beltless holddown system.
In the past, a corrugator double backer has typically utilized a wide driven holddown belt to carry the double face corrugated web over the flat heated surface of the heating section and to simultaneously provide a holddown load on the upper web surface to enhance curing of the adhesive joining the second liner web to the previously formed single face web. The driven holddown belt is also utilized to provide initial thread-up of the downstream end of a freshly glued double face web.
The advent of the beltless double backer, as described for example in co-pending U.S. application Ser. No. 08/643,627, filed May 6, 1996, has resulted in much improved double backer performance with a much simpler construction. However, the elimination of a driven holddown belt has also eliminated the common means for threading a new web into and through the double backer. Thread-up of a new web may be accomplished by hand, but it is a cumbersome procedure and must be undertaken in a typically warm and uncomfortable environment. Thus, a thread-up device for a beltless double backer would be very useful, but such a device would have to withstand the high temperature environment and would have to be located in very limited confines where it would not interfere with double backer operation. The thread-up apparatus would also have to operate in conjunction with the holddown mat lift system of the type disclosed in the above identified application.